A total of 9 patients were studied under this protocol, 7 patients had colon cancer and 2 had esophageal adenocarcinoma. Patients received I-131 labeled 45.2D9 with a dose ranging from 2 mCi to 10 mCi of I-131, and .5 mg to 18 mg; in addition, they received I- 125 labeled BL-3 in equal milligram amounts and with 1-2 mCi of I-125. The immunoreactivity of the 45.2D9 was approximately 50% with exception of 2 preparations which were over iodinated and had extremely poor immunoreactivity. Two patients were not evaluable because of poor immunoreactivity of the labeled product, although one of these patients had tumor uptake in a large liver metastases. A third patient was not evaluable because infiltration of the dose. Tumor uptake was seen in 3 of the 10 patients studied. The antibody did not concentrate to a significant extent in normal organs. Plasma clearance ranged from a T 1/2 of 24 to 48 hours. Whole body retention had a T 1/2 of slightly more than 72 hours. Gamma counting of tumor specimens showed minimal to no specificity of localization of the antibody in tumor. No further accrual into this protocol is planned.